A lens is an optical structure that refracts light thereby concentrating or diverging the beam. A lens may be a simple lens consisting of a single contiguous structure or a compound lens comprising an array of disjoined simple lenses.
Lenses are used as contact lenses and eyeglasses to improve personal vision. Lenses are also employed in a variety of optical devices including microscopes, telescopes, binoculars, projectors, cameras, etc. Lenses may also be used in Micro-Electro-Mechanical Systems (MEMS), which employ microscopic structures having dimensions ranging from atomic dimensions, i.e., nanoscale, to a few millimeters to provide modification of a path of a beam.
Operation of a lens is best understood with the focal point of the lens. The dimension between the lens and the focal point is the focal length. The focal point may be located on the side of the lens from which the light emerges, in which case the lens converges the beam, or may be located on the side of the lens on which the incident light impinges, in which case the lens diverges the beam.
Operation of a lens often requires adjustment of the distance between the lens and an imaging system, which may be a photographic film, retina of an eye, or a light conversion device such as a photosensitive diode, to provide an image without loss of image resolution. Such a requirement may arise from changes in the distance between an object and the lens, or may arise from changes in the ambient that affect the refractive index of components of a lens system, e.g., ambient temperature changes in a lens system of a large telescope in an observatory.
FIG. 1 shows an exemplary prior art lens system, in which an image sensor 110 is located in the light path behind a prior art lens 120. The distance d between the image sensor 110 and the prior art lens 120 is greater than the focal length f of the prior art lens 120. Should the need arise to alter the distance d between the prior art lens 120 and the image sensor, the relative position between the prior art lens 120 and the image sensor 110 is changed. Such a change may be effected by moving the prior art lens 120 alone, by moving the image sensor 110 alone, or by moving both the prior art lens 120 and the image sensor 110.
While such physical movements are feasible in some circumstances, requirement to incorporate a movable part into a structure typically poses a heavy burden on engineering. To enable physical movement, a motorized driver, a power supply system, and a guide system are typically needed, thereby complicating the design of a lens system. Such a requirement poses an especially serious engineering challenge in Micro-Electro-Mechanical Systems. Further, in many applications, a more compact lens design that does not employ a driving system for physical movement is preferred compared to a bulky lens system.
In view of the above, there exists a need for a lens that enables formation of a high resolution image in an optically sensitive element of an optical system over a range of distances between the lens and the object of the image, and a design structure embodied in a machine readable medium for designing, manufacturing, or testing a design for the same.
Particularly, there exists a need for a lens that may alter of optical paths to accommodate the changes in the distance between the object and the lens without changing the physical distance between the lens and the optically sensitive element, and a design structure embodied in a machine readable medium for designing, manufacturing, or testing a design for the same.